package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.CatcheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {


    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CatcheClient catcheClient;

    /**
     * 根据id查询商铺信息通过存储缓存
     * @param id
     * @return
     */
    @Override
    public Result queryById(Long id) {
        //1.缓存穿透
      Shop shop = catcheClient.queryWithPassThrough(RedisConstants.CACHE_SHOP_KEY,
               id,Shop.class, this::getById,RedisConstants.CACHE_SHOP_TTL,TimeUnit.MINUTES
       );
        //2.1互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

       //2.2利用逻辑过期解决缓存击穿
      /*  Shop shop = catcheClient.queryWithLogicalExpire(
                RedisConstants.CACHE_SHOP_KEY,
                id, Shop.class, this::getById, RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);*/
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }
 //缓存池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);
    //逻辑过期时间解决缓存击穿
    public Shop queryWithLogicalExpire(Long id){
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存 商品数据使用Redis里面的string缓存的
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否命中
        if (StrUtil.isBlank(shopJson)){  //"" "/t" null 返回false "abc"返回true
            //3.未命中直接返回
            return null;
        }
        //4.命中，需要把json反序列化对象（需要把redis里面的数据取出来）
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
         JSONObject data = (JSONObject)redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //5.1未过期 直接返回店铺信息
            return shop;
        }
        //6 已过期 需要缓存重建
        //6.1获取互斥锁
        String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //6.2判断是否获取互斥锁成功
        if (isLock){
            //6.3成功 开启独立线程 实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    this.save2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException();
                }finally {
                    unlock(lockKey);
                }
                    });
        }
        //6.4返回过期商铺信息

        return shop;
    }

    //互斥锁解决缓存击穿
    public Shop queryWithMutex(Long id){
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存 商品数据使用Redis里面的string缓存的
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)){  //"" "/t" null 返回false "abc"返回true
            //3.存在，直接返回
            //因为shopJson是json格式的所以要转换为字符串
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if (shopJson!=null){
            return null;
        }
        //4.实现缓存重建
        //4.1 获取互斥锁
        Shop shop = null;
        try {
            boolean isLock = tryLock(RedisConstants.LOCK_SHOP_KEY);
            //4.2 判断是否获取成功
            if (!isLock) {
                //4.3 失败则休眠 重式
                Thread.sleep(10);
               return queryWithMutex(id);
            }
            //4.4 成功，根据id查询数据库
            shop = getById(id);
            // 模拟重建延时
            Thread.sleep(200);
            //5.判断商品是否存在
            if (shop==null){
                stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
                //6.不存在直接返回
                return null;
            }
            //7.存在写入redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //8.释放锁
            unlock(RedisConstants.LOCK_SHOP_KEY);
        }
    //9.返回
        return shop;
    }
  //缓存穿透
/*    public Shop queryWithPassThrough(Long id){
        String key = RedisConstants.CACHE_SHOP_KEY + id;
        //1.从redis查询商铺缓存 商品数据使用Redis里面的string缓存的
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)){  //"" "/t" null 返回false "abc"返回true
            //3.存在，直接返回
            //因为shopJson是json格式的所以要转换为字符串
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        if (shopJson!=null){
            return null;
        }
        //4.不存在 ，根据id查询数据库
        Shop shop = getById(id);
        //5.判断商品是否存在
        if (shop==null){
            stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
            //6.不存在直接返回
            return null;
        }
        //7.存在写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        // 8.返回
        return shop;
    }*/
  //加上锁
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //删除锁
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    //预热现将数据缓存到redis中并设置逻辑缓存时间
    public void save2Redis(Long id,Long expireSeconds){
      //1.根据id查询数据
        Shop shop = getById(id);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id==null){
            return Result.fail("id不存在");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete(RedisConstants.CACHE_SHOP_KEY+id);
        return Result.ok();
    }
}
